Perfect binding machine

A perfect binding machine comprising:

• a conveying path;
• a series of binding units arranged along the conveying path for performing perfect binding;
• at least one clamp unit movable along the conveying path;
• a first drive mechanism moving the clamp unit along the conveying path,
• the perfect binding being performed while a book block held between a pair of clamp plates of the clamp unit sequentially passes through the binding units,
• the respective two or more binding units including a pair of members with which the book block is engaged at both sides thereof protruding from between the pair of clamp plates, and a gap adjusting unit moving the pair of members in directions toward and away from each other;
• a first control unit controlling the clamp unit and the gap adjusting unit;
• and
• a thickness measurement unit measuring a thickness of the book block,
• wherein before start of the perfect binding, the thickness of the book block is measured by the thickness measurement unit, and the gap between the pair of clamp plates and the gap of the respective pair of members are adjusted by the first control unit based on the measured value of the thickness, characterized in that
• the thickness measurement unit includes:
• a base having an upper surface on which the book block is placed;
• a stationary body attached to the upper surface of the base and having a reference surface perpendicular to the upper surface;
• a guide rail attached to the base and extending perpendicularly to the reference surface;
• a movable body mounted on the guide rail for slide movement in directions toward and away from the stationary body;
• and
• a second drive mechanism sliding the movable body along the guide rail,
• the movable body having two surfaces which are spaced from each other in a direction of an axis of the guide rail, a space being formed between the two surfaces,
• the thickness measurement unit further includes:
• a measuring body arranged in the space of the movable body and mounted on the guide rail for slide movement between the two surfaces, and having a measuring surface opposed to the reference surface of the stationary body;
• one or more elastic biasing members arranged between the movable body and the measuring body for constantly pressing the measuring body against a surface closest to the stationary body of the two surfaces;
• a first sensor attached to the base or the stationary body so as to detect a time when the book block is placed in front of the reference surface of the stationary body;
• a second sensor attached to the movable body, or the measuring body, or the both so as to detect a time when the measuring body is separated from the surface closest to the stationary body by a predetermined distance against an elastic force of the elastic biasing member;
• a travel distance measurement unit measuring a travel distance of the measuring surface from the reference surface, a zero point of the travel distance being established as a point at which the measuring surface of the measuring body contacts the reference surface of the stationary body;
• and
• a second control unit controlling the second drive mechanism and the travel distance measurement unit, and that,
• when the first sensor outputs a detection signal, the movable body further slides toward the stationary body after the measuring surface of the measuring body comes into contact with the book block so as to press the book block against the reference surface and then, when the second sensor outputs a detection signal, the movable body stops and the measurement is performed by the travel distance measurement unit to obtain the thickness of the book block.